Manifold microchannel heat sink design using optimization under uncertainty

Abstract

A three-dimensional numerical model is developed and validated to study the effect of geometric parameters such as microchannel depth and width, manifold depth, and manifold inlet and outlet lengths on the performance of a manifold microchannel (MMC) heat sink. The manifold arrangement used to distribute the flow through alternating inlet and outlet pairs greatly reduces the pressure drop incurred in conventional fluid supply arrangements due to its shorter flow paths, while simultaneously enhancing the heat transfer coefficient by limiting the growth of thermal boundary layers. The computational analysis is performed on a simple unit-cell model to obtain an optimized design for uniform thermal boundary conditions, as well as on a porous-medium model to obtain a complete system-level analysis of multiple microchannels across one manifold. The porous-medium approach can be further modified to analyze the performance under asymmetrical heating conditions. Along with conventional deterministic optimization, a probabilistic optimization study is performed to identify the optimal geometric design parameters that maximize heat transfer coefficient while minimizing pressure drop for an MMC heat sink. In the presence of uncertainties in the geometric and operating parameters of the system, this probabilistic optimization approach yields a design that is robust and reliable, in addition to being optimal. Such an optimization analysis provides a quantitative estimate of the allowable uncertainty in input parameters for acceptable uncertainties in the relevant output parameters. The approach also yields information such as the local and global sensitivities which are used to identify microchannel width and manifold inlet length as the critical input parameters to which the outputs are most sensitive. The deterministic analysis shows that the heat transfer performance of the MMC heat sink is optimal at a manifold inlet to outlet length ratio of 3. A comparison between the deterministic and probabilistic optimization approaches is presented for the unit-cell model. A probabilistic optimization study is performed for the porous-medium model and the results thus obtained are compared with those of the unit-cell model for a uniform heat flux distribution.

A hierarchical manifold microchannel heat sink array for high-heat-flux two-phase cooling of electronics

“…The plenum interface plate is designed to have equal total inlet and outlet flow areas. Previous designs in the literature that were optimized for single-phase flows found the optimal inlet-to-outlet area ratio to be approximately 1.5:1 to 3.5:1 [29,32]; an increased outlet plenum size was incorporated in the current design to limit contraction of the high-velocity two-phase mixture at the channel outlet. One side of the plenum plate is mated to a 10 μm-thick double-sided adhesive and brought into contact with the manifold; the opposite side of the plenum plate is bonded to the microchannel plate ( Figure 2).…”

“…A variety of researchers have conducted numerical studies to identify optimized geometries and operating conditions for both the fluid distribution manifold and microchannel heat sink [28][29][30][31][32]. These studies concluded that 1) at a fixed pumping power, there is an optimal channel height, channel width, and flow length for which thermal resistance is minimized, 2) the flow length should be minimized to minimize pressure drop for a fixed heat flux until manifold pressure drop governs the overall pressure drop at extremely short flow lengths, and 3) decreasing the channel width and increasing the flow rate both increase the heat transfer rate at the cost of increased pressure drop.…”

Enhancement thermodynamic performance of microchannel heat sink by using a novel multi-nozzle structure

“…5c presents the temperature profiles of the models with channel lengths of 1 mm, 3 mm and 5 mm for both base-lines 1 and 2. The results show that the bottom wall temperatures of the models with a shorter channel length were lower and more uniform than those for longer channels [26,27]. More specifically, with a channel length of 1 mm, the differences between the maximum and minimum temperatures on the bottom wall were 2.39°C and 2.56°C for the MN-MCHS with base-lines 1 and 2, respectively.…”

“…In 2012, Boteler et al [26] were first to propose the concept of a manifold microchannel heat sink (M-MCHS). Following that proposition, the investigations on the M-MCHS were continued by other groups of authors [27][28][29]. They reported that the M-MCHS could significantly reduce the pressure drop and improve the temperature uniformity on the bottom wall due to the truncation of the path of the coolant.…”

Multi-objective modeling, uncertainty analysis, and optimization of reversible solid oxide cells

“…There are commonly two types of uncertainties: aleatory and epistemic [29,30]. Aleatory uncertainties are associated with physical variability (e.g., material properties, operating condition manufacturing, and tolerance) in the system and environment which are typically handled using probabilistic methods.…”